Light projector



April 8, 1952 H, E, SMITH 2,592,075

LIGHT PROJECTOR Filed June 25, 1950 3 Sheets-Sheet l Him.

I h 35 L WI, 3 INVENTOR.. 3'7 36 //41 P040 E 5411i ay. 5: j eu April 8, 1952 H. E. SMITH 2,592,075

LIGHT PROJECTOR Filed June 23, 1950 3 Sheets-Sheet 2 INVENTOR. 7 flmwlpf. 5311114 April 8, 1952 H. E. SMITH 2,592,075

LIGHT PROJECTOR Filed June 25, 1950 3 Sheets-Sheet 5 Patented Apr. 8, 1952 UNITED STATES PATENT OFFICE LIGHT PROJECTOR Harold E. Smith, Lykens, Pa.

Application June 23, 1950, Serial No. 169,869.

'20 Claims. (!..313-114) This invention relates to an improved light vision of a light projector formed of a plurality of individual projectors in such manner as to permit fabrication by molding or die pressing a minimum number of elements or parts which may be hermetically sealed together to form the integrated projector.

A further object of my invention resides in the combination of a plurality of light sources and reflectors in such manner as to yield an integrated automobile headlamp devoid of glare and in which the light sources are positioned above I the horizontal level of the beam cut-off so as to be invisible to approaching drivers and pedestrians.

A still further object of my invention resides in the provision of a single automobile headlamp Y requiring only one adjustment to the vehicle to project a proper light beam superior to that obtainable with a plurality of headlamps each requiring separateadjustment, and which may be so placed with respect to a vehicle as to protect the lamps from damage and disalignment when the vehicle fenders are damaged.

Still another object of the invention lies in the provision of an integrated automobile headlamp comprised of a plurality of light sources and reflectors which, in addition to a normal driving beam, projects an upwardly angled warning or signal beam.

A still further object of my invention resides in the construction of a multiple light projector comprising a plurality of projectors integrated into a single unit capable of simple fabrication at a lower cost than an equivalent number of individual projectors.

For the attainment of these objects, and additional features and advantages as may hereinafter appear or be pointed out, I have illustrated 2 light projector formed in two parts and shown separated prior to sealing together into one unit;

Figure 2 is a section of the forward part or element taken on line 22 of Fig. 1;

Figure 3 is a section of the rearward part taken on line 3--3 of Fig. 1;

Figure 4 is a top plan view of the light projector looking in the direction of the plane of its. sealing flange;

Figure 5 is a front'elevation of the light projector Figure 6 is a perspective view showing the manner of forming one. of the rearwardly positioned ovoid reflectors;

Figure 7 is a perspective view similar to that of Fig. 6, showing the method of generating one of the forwardly positioned ovoid reflectors;

Figure 8 is a diagrammatic front elevation showing the horizontal spread of rays reflected from one of the forward ovoid reflectors when the ovoid reflector is generated to include an elliptical directrix in a vertical plane;

- Figure 9 is a diagram similar to that of Fig. 8,

but showing the distribution of reflected light from the ovoid obtained by modifying the ovoid directrix to a parabolic curve;

Figure 10 is a diagram similar to Fig. 9, showing the spread of lightrays from an ovoid having a modified directrix which is hyperbolic;

Figure 11 is a diagram similar to Fig. 9, showing the spread of light rays from an ovoid having a modified directrix which is a mixed and blended conic section curve partially elliptical and partially hyperbolic;

Figure 12 is a diagrammatic, vertical sectional view bisecting any one of the ovoid reflectors of the light projector and showing the paths ofreflected rays and their vertical distribution;

Figure 13 is a diagram similar to Fig. '12, showing the path of rays forming the warning beam; Figure 14 is a diagrammatic top plan view showing the horizontal distribution of light beams from the laterally positioned individual light sources in the integrated light projector;

Figure 15 is a diagrammatic view, showing the vertical distribution of rays from the integrated light projector impinged on a vertically posi-.

tioned screen which is represented for clarity as being swung aside on its center line;

Figure 16 is a diagrammatic front view offiie visible portion of my unitary headlamp when installed on a vehicle; and

Figure 1'7 is a diagrammatic plan representation of light. source images reflected from one of descence.

3 the ovoidal reflectors to the trimming edge of the reflective shield;

My improved light projector I comprises a rear section I I and a front section or element l2, the two sections being adapted to be hermetically sealed together at their respective sealing flanges l3 and 14.

The rear element ll includes a reflector 15 which is parabolic in vertical section and cylindrical in shape so that its focal line represented by point IS in Fig. 3 is parallel to its upper and lower edges, I1 and I8, respectively. Horizontal sections through this reflector are straight lines also parallel to the focal line. Superimposed on the cylindrical reflector l are a plurality of ovoidal reflectors 20 connected thereto by nonreflecting surfaces 2 l. The reflectors 20 are connected to each other and to the peripheral sealing flange by connecting surfaces 22 at the top of the element and surfaces 23 at the sides. Reflector I5 is also connected to the sealing flange I3 by surfaces 23 at the sides which may be reflective and by surface 24 at its bottom. Each of the ovoidal reflectors 20 is provided with a separate light source 25 which is preferably a helically wound filament of small diameter presenting a short line of bright light when electrically heated to incan- The filament supports 26 serving as electrical conductors may be embedded in projecting posts 21 of insulating material to support the filaments in substantially the proximate focal regions of the ovoid reflectors 20.

The mating projector element 12 is provided in its upper portions with a plurality of forwardly protruding ovoidal reflectors 30 each of which has a proximate focus substantially coincident with one of the light sources 25, and a remote focal line or area substantially coincident with the focal line l6 of the cylindrical reflector. The reflectors are connected to each other at their upper edges and to the sealing flange l 4 by non-reflective surfaces 3|. Each reflector 30 is completed at the bottom by an oblique reflecting shield 32 whose lower edge 33 is straight and positioned slightly forward of focal line [6 of the cylindrical reflector when the two mating projector halves are united at their flanges l3 and [4. -The lower edges of the reflectors 30 and shield 32 are joined to a substantially vertical, transparent front closure surface 36 by a substantially horizontal surface 35. Shield 32 and member 35 are provided with transparent areas 34 and 34 respectively for purposes to be hereinafter explained. Surface 31 connects the outermost reflectors 33 to the sealing flange while surfaces 38 and 39 connect closure 36 at its bottom and sides to the sealing flange and to surface 35. Connecting surfaces 31, 38 and 39 are normally non-reflective also,

- since direct rays from light sources 25 will not usually reach these surfaces.

The sealing flange l4, as well as its counterpart I3, is preferably disposed at an oblique angle to the vertically disposed boundary edges of the reflectors 20 and 30 as best shown in Figs. 2 and 3.

Referring particularly to Fig. '7, there is illustrated a preferred method of forming the ovoid reflectors 30. The illustrated vertical plane 40 is a directrix plane which includes the light source 25 and the focal line 16 of reflector IS. The horizontal plane shown at 4| includes the surface 35 and the lower edge 33 of the reflective shield 32, which is coincident with or spaced only slightly in front of focal line [6. The oblique plane 42 includes the reflective shield 32. An

elliptical curve 43 lying in the vertical plane 40 and having foci 25 and 45 may be used as a directrix for generation of the warped surface 30. The primitive generating curve 46 lies in a plane normal to plane 40 and includes the points 25 and 45. The generatrix 46 is a segment of an ellipse having foci at 25 and 4 4, the latter point being one which falls on line l6. In generating the reflecting surface 30 the generatrix 46 is moved in planes perpendicular to 40 and varied in size, diminishing as it moves away from its initial position in both directions as indicated at 46,46" and 46", while including as directrices the elliptical curve 43, along which moves the vertex of the generatrix. and the line l6 along which moves the remote focus 44 of the generatrix. When fashioned inthis manner the ovoid reflector 30 will reflect rays from light source 25 vertically toward focus 44 lying on focal line I6 while converging the rays horizontally toward focus 45 to form a remote focal line or region approximately coincident with focal line l6 of the ultimate reflector. It should be noted that reflector 30 as thus far described is a warped surface generated somewhat similarly to certain of those disclosed in Patents 1,913,518 and 1,913,519, issued jointly to myself and Harry E. Buffington on June 13, 1933, and that other methods of generating such ovoidal reflectors disclosed therein may equally well be used in subject invention provided that when formed they are disposed more vertically than horizontally was to permit use of a pair of ovoids at the front and rear of a light source and provided further that the remaining parts of the combination are modified in design to match. 7

The front of reflector 30 is in effect sliced off at any convenient angle by plane 42, representing the plane of the shield or baffle 32, which forms a curved connecting edge 49 with the reflector.

The rearwardly disposed ovoids 20 are warped surfaces generated in a manner similar to that described for reflectors 30. As illustrated in Fig. 6 the same ellipse 43 with foci at 25 and 45 may be used as a directrix in vertical plane 40. The primitive generating ellipse 50 and its smaller counterparts 50 and 50" on each side of a vertical reflector bisecting plane are, however, preferably formed as blended curves including at least two elliptical portions. The uppermost portion a of the generatrix are 50 is an elliptical segment having foci at 25 and 44, the latter lying on focal line l6. The lowermost segment I) of the generatrix is tilted with respect to a and is preferably a section of an ellipse having one focus at 25 and the remote focus at a point 55 spaced below and forwardly of focal line l6 but in such position that all rays from 25 reflected by section b pass behind focal line l6, see Fig. 12. In all other respects ovoids 20 are generated in a manner exactly similar to that utilized and previously described with respect to reflector 30 except that no shield equivalent to 32 is required. Y Y

When the-two halves of the headlamp are sealed together along their sealing flanges, it will be 'noted that each light source 25 is located in or near the proximate focus of a vertically disdrivers .or pedestrians. -usefulto. warn drivers of the approach of we illustrated in Fig. 12. From this figure it will be evident that forwardly directed rays r are reflected by ovoid- 30 through the focal line I 6 of the parabolic reflector I so that upon impingement on the latter they are reflected a second time in horizontal planes through the front transparent cover 36. Rays a striking the uppermost section of the rearwardly disposed ovoid are also re.-

flected through focal line I6. Rays a strike the parabolic reflector I5 and are reflected forwardly in horizontal planes. Rays 1) are reflected by the lower portion of the ovoid 20 to its remote focal line 55 and upon impinging the parabolic reflector in this region are re-reflected to emerge from the headlamp in downwardly angled directions adapted to light the roadway adjacent the vehicles. The rays s which strike the lowermost portions of the reflecting shields 32 are reflected to the cylindrical reflector I5 as if from a source positioned rearward of its focal line I6, and consequently these rays are also reflected to emerge from the headlamp at slight downward angles.

The upwardly directed signal beam is formed by rays S passing through the transparent areas 34 and 34 in members 32 and. respectively, and striking the parabolic reflector as if from a source located in front of its focal line I6, see Fig. 13. These rays are therefore reflected to emerge from I the headlamp at an upward angle which may. be

selected to avoid glare in the eyes of oncoming A beam so directed" is hicles along roads crossing the highway and particularly in foggy weather.

Figure 8 illustrates the paths of rays reflected from a front ovoid 30 and lying in the plane of itszrear; vertical boundary edge, that is inplane of Fig. '7. Such rays are reflected to converge toward remote focus of directrix ellipse 43. Rays striking other portions of reflector 30 are also reflected substantially through focal line I6 and similarly converge toward a reflector bisecting plane and more particularly toward acircudifferent ellipses as directrix.

Fig. 17 illustrates sample images L of the light source '25, after reflection from surface 20 or 30, intersecting the lower trimming edge 33 of the re flective shield 32 before striking the cylindrical reflector I5 and shows how this edge chops ofl? small portions of the images to prevent light from reaching the parabolic reflector I5 from points forward of its focal line I6 which is substantially coincident with edge 33. c

If the horizontal spread of the light beam from the Projector unit is desired to be small or en tirely .eliminated, the reflectors 38 and their mating portions 20 may be generated as de- B I scribed and illustrated mile. 7; usinginsteadlof the elliptical clirectrix 43a vertically positioned parabolic curve such as 56 shown. in Fig- 9. When the reflector is so. formed rays from the proximate focus 25 will be reflected. without convergenceror divergence. A hyperbolic 'direic trix curve such as 41 also be used in place of ellipse 43 to obtain different horizontal divergence of the reflected light rays as illustrated in Fig. 10. Any mixed and blended conic section are may be used as directrix and substituted for the ellipse 43 in order to obtain a prescribed horizontal light distribution, there being shown one such curve 48. Fig. l 1, whichis partially elliptical (on the right as viewed in. the figure) and partially hyperbolic '(on. the left) and so disposed as to angle all rays from the proximate focus 25 in one horizontal direction upon reflection from the ovoid 30 or 20.

' In fabricating the headlamp, the rear and front elements I2 and II are formed from suitvable material such as glass or metal and the reflecting surfaces coated or electroplated as at 52 with an eificient light reflector such as silver. All of the surfaces are so curved as to permit molding or die pressing each element. The selection of an oblique angle for placement of the sealing flanges I3 and I4 permits the inclusion in one element of the headlamp'of' the entire cylindrical reflector and at the same time permits the molding of the combined ovoidal reflectors in separate,.vertically split halves. In each element suflicientdraft is allowed to permit easy shedding of the dies or-molds, and for this purpose also, certain'of the reflector connecting surfaces such as 23, 3'Iand. 39 are i'ounded. The cutting off of. thesharp corners at the sides. of reflector '15 does not materially aflect the light beam providing only a wider horizontal spread from these portions to light thesides of the roadway close to the front of the car in which the aheadlamp is mounted.

. tensity horizontal portions of the headlamp beam the presence ofjthe notches 5I facilitates molding without lessening the intensity of the beam. The light source supporting stems 21 1 may be integrally formed in the rear element when both are of glass or may be separately formed and sealed fill proper position. Upon joining the front and rear halves, the interior of the headlamp is evacuated or filled with a rare gas while the sealingflangesare fused together to form an hermetic joint.

Referring to Fig. '14 it will be apparent that the resultant beam obtained from my improved headlamp is composed of horizontally overlapping beams from thefthree light sources 25. The

, beam -6I from the central. source and the pair of central reflectorsiZile-iill diverges forwardly in a fan shape. The beams 62 and B3 are preferably crossing beams; from the two outer light sources obtained by, displacing or shifting the light sources with respect to the proximate foci of their respective ovoid reflectors or by use of mixed conic sefction curves as directrices for the ovoids as illustratedinFig, 11. The composite beam obtained is shown in Fig. 15 as 7 it would appear on a vertical screen 66. The driving beam 60 has a relatively sharp cut-off line in a horizontal level including .the head lamp surface 35 and this beam is separated by a relatively darkened area 65 from the signal or warning beam 10. The combination of reflectors employed in the headlamp serves to deflect rays, that would normally emerge upwardly, into the beam 60 making this beam more intense and correspondingly subduing the upwardly directed straylight as represented by 65 on the screen.

The presence of the trimming edge 33 of the reflective shield acting in the manner illustrated in Fig. 17 insures that no rays will strike the parabolic reflector as if coming from a source in front of its focal line and consequently the beam will be projected forwardly and downwardly with no light emerging in upward directions other than the intended signal beam and a very minor amount of stray light incident to multiple reflections from the transparent closure 36 and certain of the other connecting surfaces. The stray light maybe even further reduced by coating or painting'the inner sides of some of the connecting surfaces with a light absorbent medium.

The headlamp may be mounted in a vehicle with all parts concealed save the transparent front surface 36, as diagrammatically shown in Fig. 16. Preferably the mounting will be made to the rear of a protecting bumper and centrally of the vehicle to avoid damage likely'to occur when placed at the sides in the fenders. When thus mounted one vertical adjustment to the vehicle is sufficient to adjust the composite beam from the three reflector combinations illustrated. It

is apparent that while only three ovoid reflector combinations have been shown and described any desired smaller or larger number of combi-- nations may be employed. The additional reflector combinations may be added laterally, in which case the parabolic reflector and the transparent cover 36 may also'be widened as indicated at 36 in Fig. 16.v

Wnile I have described my invention in its preferred form as comprising a vehicular headlight it will be understood that its application may be general'an'd not limited to such use. For example, the projector may be applied to the lighting of billboard or building structures and its beam need not be horizontally projected. Various other modifications may be made in form, detail and arrangement of parts of the illustrated embodiment without necessarily departing from the 'scope and spirit of the invention as set forth in a plurality of light sources, and a plurality of additional reflectors constructed and arranged 'toreflect rays from the light sources to the cylindrical reflector substantially through and on one side of its focal line, said projector being formed in two parts each having a peripheral flange, juxtaposed andsealed together.

2. A light projector comprising, a plurality of light sources, a plurality of ovoid reflectors, a f cylindrical reflector having a focal line, a reflective shield'having a straight edge, said light sources being positioned substantially in the prox- 8 imate foci-of said ovoid reflectors, and the remote foci of said ovoids being substantially coincident with the focal line of the cylindrical reflector and said edge of the reflective shield.

3. A light projector as described in claim 2 wherein light rays from said sources impinging said cylindrical reflector are projected through a transparent member and said ovoids, cylindrical reflector and reflective shield are connected together by non-reflecting surfaces.

4. A multiple headlamp as described in claim 2 wherein said reflective shield is provided with a transparent area positioned on one side of the focal line of the cylindrical reflector whereby rays from the light sources passing through said transparent area strike the cylindrical reflector and are reflected to form an angled signal beam.

5. A light projector comprising a cylindrical reflector having a horizontalfocal line and vertical parabolic sections, a light source positioned above said focal line. a pair of ovoid reflectors superimposed on the cylindrical reflector and positioned forwardly and rearwardly of the light source, said ovoid reflectors having a proximate focus coincident with the light source and a remote focal line substantially coincident with the focal line of the cylindrical reflector, and a reflecting shield intersecting said forwardly positioned ovoid at an oblique angle and terminating in a'substantially straight line trimming edge slightly forward of the focal line of the cylindrical reflector.

6. A headlamp as described in claim 5, wherein each of said ovoids is a blended surface generated by ellipses of varying size having a conic section curve as a directrix, said ellipses extending in the inherent focal reflecting angle of the directrix.

'I. A multiple light projector comprising a plurality of light sources, a cylindrical reflector having parabolic sections and a focal line positioned below said light sources, a plurality of forwardly positioned ovoid reflectors each having a, proximate focus coincident with one of said light sources and a remote focal line coincident with the focal line of the cylindrical reflector, a reflective shield provided with a straight edge spaced slightly forward of the focal line of the cylindrical reflector, and a plurality of rearwardly posi tioned ovoids having proximate foci coincident with the light sources and having remote foci positioned so that reflected rays pass rearwardly of said edge of the reflective shield.

8. Amultiple headlamp as described in claim 7 wherein each of said ovoids are blended surfaces generated by a substantially vertical ellipse of varying size having a conic section curve as a directrix lying in a substantially vertical plane normal to the plane of the generating ellipse.

9. A multiple headlamp as described in claim 7 wherein each of said ovoids are blended surfaces generated by a substantially vertical ellipse of varying size and having a directrix which is a blended and mixed conic curve lying in a substantially vertical plane containing said focal line of the cylindrical reflector; Y

10. A multiple'headlamp as described in claim 7 wherein each of said ovoids are surfaces formed by a substantially vertical, elliptical generatrix of varying size having one directrix for its vertex. which is a conic section curve lying in a plane which includes'said focal line of the cylindrical reflector and said light sources and which is normal to the generatrix, and having a second directrix for its remote focus which is a straight line 9 coincident with said focal line of the cylindrical reflector.

11. A headlamp as described in claim 7, wherein each of said ovoids is a blended surface generated by ellipses of varying size having a conic section curve as a directrix, said ellipses extending in the inherent focal reflecting angle of the directrix.

12. A headlamp as described in claim '7, wherein each of said ovoids is a blended surface generated by ellipses of varying size having a directrix which is a blended and mixed conic curve lying in a plane containing said focal line of the cylindrical reflector, said ellipses extending in the inherent focal reflecting angle of the directrix.

13. A multiple projector comprising, a plurality of light sources, a plurality of forwardly positioned ovoids whose proximate foci are coincident with the light sources, said ovoids being transected by an oblique reflecting shield terminating in a substantially straight edge which is located at their remote focal lines, a plurality of rearwardly positioned ovoids having proximate foci coincident with the light sources and remote focal lines coincident with said edge of the reflective shield, a cylindrical reflector positioned below the last named ovoids and having parabolic sections and a focal line coincident with said edge of the reflective shield, each of said forwardly positioned ovoids being blended surfaces generated by a substantially vertical ellipse of varying size and having a conic section curve as a directrix in a vertical plane, normal thereto and which includes said edge of the reflective shield, each of said rearwardly positioned ovoids being warped surfaces generated by a substantially vertical mixed and blended conic curve of varying size and having a conic section are as a directrix lying in said vertical plane which includes the directrix of the forwardly positioned ovoid.

14. A multiple light projector comprising a plurality of light sources, a plurality of ovoid reflectors positioned with their proximate foci coincident with the light sources, a cylindrical reflector having a focal line coincident with the remote foci of said ovoid reflectors, a reflective shield terminating in a straight edge coincident with the focal line of said cylindrical reflector, said projector being formed in a plurality of parts each provided with mating flanges and hermetically sealed at said flanges.

15. A light projector element comprising a cylindrical reflector having a focal line, a plurality of ovoid reflectors superimposed on the cylindrical reflector and connected thereto by non-reflective surfaces, said ovoid reflectors having remote foci in the region of the focal line of the cylindrical reflector, and a perimetric flange for sealing said element to a mating section of a light projector.

16. An element for a light projector as described in claim 14, said element being additionally pro vided with a plurality of light sources positioned at the proximate foci of said ovoid reflectors.

17. A light projector element as described in claim 14 wherein said flange falls in a plane extending from above the ovoid reflectors to the bottom edge of the cylindrical reflector.

18. A light projector element comprising a plurality of laterally spaced ovoid reflectors each intersected by a planar reflector extending from the surfaces of the ovoids to a line containing the remote foci thereof, said planar reflector being connected by a non-reflective surface to a transparent surface, said reflectors and surfaces being bounded by and connected to a peripheral flange for sealing to a mating section of a light projector.

19. A light projector element constructed as described in claim 18 wherein said flange extends in an inclined plane from above the ovoid reflectors to below the bottom of said transparent surface, said ovoids and transparent surface lying on one side of the plane and said planar reflector extending across the plane of the sealing flange.

20. A light projector comprising, a cylindrical reflector havingv a focal line and adapted to project rays from said focal line in parallel planes, a light source positioned above said focal line, a truncatedovoidal reflector superimposed on the cylindrical reflector and so positioned with respect to the light source as to'reflect rays therefrom to the cylindrical reflector substantially through and on one side of its focal line, said ovoidal reflector being split in a plane which includes the light source and said focal line and said projector being split in a plane inclined to said first named plane. HAROLD E. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,351,169 Hotchkin Aug, 31, 1920 1,913,519 Smith et al June 13, 1933 2,288,352 Henderson June 30, 1942 

